Preparation, Properties, and Mechanism of Novel Polyurethane Adhesive/Organic Montmorillonite Nanocomposites

Novel polyurethane adhesives (PUA) were prepared by the incorporation of organic montmorillonite (OMMT). The structure of the PUA/OMMT adhesives was analyzed by wide angle X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. It was observed that the OMMT layers in the PUA were of nanometer dimensions and the molecular structure of PUA was perturbed by the presence of OMMT. This was due to the reaction between the monomers and the intercalation agent. Physico-mechanical properties such as adhesion and thermal stability were investigated. Results showed that the PUA system with 3 phr OMMT has the best physical and mechanical properties due to the exfoliation of OMMT. The nano-reinforcing effect caused by the exfoliated silicate layers may reduce the amount and size of voids during peeling, which can increase the length of the crack path in their vicinity, leading to improved adhesive properties. This is postulated as the mechanism for improved adhesion in the PUA/OMMT adhesive.